Circuit organization for magnetrons



Jan. 13, 1942. H. BERGER CIRCUIT ORGANIZATION FOR MAGNETRONS Filed April 15, 1939 INVENT OR. HERMA NN BER GER ATTORNEY.

Patented Jan. 13, 1942 FICE CIRCUIT ORGANIZATION FOR MAGNE- TRON S tion of Germany Application April 15, 1939, Serial No. 268,075 In Germany March 16, 1938 5 Claims.

The present invention relates generally to high frequency amplifier circuits and more particularly to circuits employing magnetrons.

In accordance with the present invention circuit arrangements are provided utilizing a magnetron tube wherein the control segments of the tube are mounted at a distance from the cathode that is greater than that of the signal or output electrodes and are maintained at such a potential that the electric field is undistorted; that is, the field between the cathode and inner segments is substantially identical with that produced by a cylindrical plate.

With this arrangement, even in the presence of the same anode potential the bombardment of the control segment pair by electrons is prevented. On the contrary, it is possible to impress upon the control plates an anode potential raised at the ratio of the squares of the radii Ra /Ri with the result that the field distribution in the interior of the magnetron is as in the ordinary magnetron type of tube; that is to say, the virtual cathode, in static condition, is given the form of a co-axial cylinder shell.

In the accompanying drawing,

Figure 1 illustrates the invention applied to an amplifier;

Figure 2 is a diagrammatic showing of one way in which a magnetron tube may be constructed in accordance with the invention;

Figure 3 illustrates a frequency multiplying arrangement using the features of the present invention;

Figure 4 illustrates the invention applied to a three phase amplifier; and,

Figure 5 illustrates in diagrammatic form a detector circuit incorporating certain features of the invention.

In Figure 1, the control or input electrodes are shown at l and 2 while the output electrodes are shown at 3 and 4. It will be noted that the control electrodes l and 2 are at a greater distance from the cathode H than output electrodes 3 and 4. The potentials applied at A1 and A2 are such that energy transfer in any other way than by the electron current is avoided.

Fig. 2 shows by way of example an arrangement in which the symmetry of construction is insured in a simple manner. In order to prevent RF voltages being induced in the heating-current supply leads, the heater current is conducted by means of a jacketed wire through the squash so that jacket and core serve for the lead and return. Shell and core of the said jacket wire must be separated by an insulator (glass, ceramic, etc.).

The heater line is symmetrically brought out of the tube between the Lecher-wire system.

As well known from the normal magnetron tube, the two useful signal or output segments may be connected with each other, and the oscillatory circuit tuned to the double frequency can then be connected between segments and cathode, as shown in Fig. 3, where l and 2 are the control electrodes, and 3 and 4 are the useful or output electrodes.

The circuit organization is capable also of a greater number of control and output electrodes than two, especially in schemes where the tube is used as a multi-phase amplifier or more particularly as a three-phase amplifier. (Fig. 4.)

The above-mention ed tube according to the present invention, could also be used readily as asignal rectifier having a working range extending all the way from the AF to the ultra-high-frequency bands. An arrangement adapted thereto is shown in Fig. 5. Impressed upon the pair of control segments l, 2, is the potential picked up by the aerial which is to be rectified, while in the lead to the inter-connected output segments is taken off the rectified modulation voltage. The magnetic field intensity, according to the frequency band in which one operates in a given case, may be chosen near the critical field intensity or else far higher than that. The advantage of this circuit organization in contrast to diodes and detectors used in the short-wave ranges primarily resides in the fact that the control action is nearly free from energy dissipation, without the transit time playing incidentally any essential part at all; moreover, the rectifier is quite useful also inside the centimeter or microwave ranges. Also in this case it is feasible to work with several pairs of segments and to rectify multi-phase currents.

It is true, fundamentally speaking, that similar tubes have been disclosed in the prior art, though these serve for modulation. In such earlier tubes, the modulation segments must be impressed with negative potentials, while the control segments of the invention are impressed with a positive biasing voltage. In another similar arrangement the outer and the inner are united with one another, whereby a smoother initiation of the oscillations in cases of self-oscillatory schemes is insured; in other words, both the inner and the outer segments are useful electrodes.

In Figures 1, 3, 4 and 5, R represents the tube envelope while M represents the external coil for inducing a magnetic field parallel to the cathode between the segments and the cathode. The elements R and M have been shown in a fragmentary manner in order to avoid confusion with the leads from the various tube elements.

I claim:

1. In signalling apparatus and the like an electron discharge device provided with a cylindrical thermionic cathode, a pair of inner electrode segments symmetrically spaced around said cathode, a pair of outer electrode segments symmetrically spaced around said cathode but opposite the gaps between said inner electrode segments, and so that the normal between the two inner electrodes and the normal between the twoouter electrodes intersect at a point which is near the axis of the cathode and are substantially normal to each other, a coil for inducing a magnetic field between the cathode and said electrode segments parallel to the cathode means for maintaining'bothof said pairs of electrodes positive with respect to said cathode, a control circuit connected between said pair of outer electrodes, said control circuit including .means' for impressing signal energy thereon, an output circuit connected between said pair of inner electrodes and means for coupling said output circuit to a utilizing device, said outer electrodes beingmaintained at such a potential relative to the inner electrodes that the electric field between the cathode and the inner electrodes is substantially identical as that which would be produced by a cylindrical electrode.

2. The arrangement described in the preceding claim characterized by that thepositive potential impressed upon the outer pair of electrodes is substantially equal to the positive potential applied to the pair of inner electrodes multiplied by the ratio of the square of the distance of said outer electrodes from the cathode and the square of the distance of said inner electrodes from the cathode.

3. In signalling apparatus, an electron discharge device having a straight thermionic cathode, a plurality of inner electrode segments symmetrically spaced around said cathode and an equal number of outer electrode segments symmetrically spaced around adjacent cathode opposite the gaps between said inner electrode segments, a coil for inducing a magnetic field between said cathode and said electrode segments parallel to the cathode means for maintaining said inner electrode segments at a positive potential with respect to the cathode, means for maintaining said outer electrode segments at a sufllciently higher positive potential with respect to the cathode to produce a substantially radial field around said cathode, an input circuit for said apparatus including means for impressing signal energy upon all of said outer electrode segments, a utilizing device, an output circuit for said apparatus connected to said inner electrode segments, and means for coupling said output circuit to the utilizing device.

4. In signalling apparatus, an electron discharge tube provided with a cylindrical cathode, a pair of opposed arcuate plates forming electron collecting electrodes positioned substantially concentric-with and displaced substantially equally from'said cathode and a pair of opposed arcuate plates forming control electrodes positioned substantially concentric with and displaced substantially equally from the cathode but at a greater distance from said cathode than said first pair of electrodes and so that the normal between the first pair of electrodes is substantially at right angles to the normal between the second pair of electrodes, a coil for inducing a magnetic field parallel to the cathode between the cathode and said plates, means for maintaining said first pair ofelectrodes atapositive potential with respect to the cathode, means for maintaining the second pair of electrodes at a positive potential with respect to the cathode which isof the order of the positive potential applied to the first pair of electrodes multiplied by the ratio of the square of the distance between one of said second named electrodes and the cathode and the square of the distance between one of the first named electrodes and the cathode.

5. In a signalling apparatus as described in the preceding claim, a control circuit connected between said pair of control electrodes and including means for impressing control voltage upon said electrode, an output circuit connected between said electron collecting electrodes and means adapted to couple the output circuit to a utilizing device.

HERMANN BERG-ER. 

